The present invention relates to patch antennas, and more particularly to an improved patch antenna utilizing matching means for improving the performance thereof.
One known form of antenna, known as a patch antenna, utilizes a planar patch of conductive material disposed parallel to a ground plane and separated therefrom by a thin dielectric layer. A feed is provided to communicate electromagnetic energy to or from the patch, and a shorting pin shorts the center area of the patch to the ground plane through the dielectric so as to fix the center of the patch at a ground potential. Antennas of this nature may be inexpensively manufactured and may be readily formed into low cost, light weight phased array antenna systems.
One difficulty with patch antennas is their narrow bandwidth. In patch antennas previously reported, the bandwidth of the antenna was as narrow as one or two percent of the center frequency of the antenna. Although in theory the bandwidth of the antenna should increase as the dielectric layer separating the patch from the ground plane is increased in thickness, the actual results produced by increasing the dielectric thickness have in the past fallen short of theory. Increasing the dielectric thickness actually further narrowed the bandwidth of the antenna, while also substantially increasing the mismatch between the antenna and the feed, producing inefficient operation.